Node setup for combining baked Diffuse Indirect, Direct, and Color passes
There is problem with you nodes. You have a color mix node after the BSDF Shader nodes. That does not work.
Using the same type of setup with three images for Indirect, Direct, and Color this is how the nodes should look. Notice the indirect and direct are added together. Then the color is mixed in with another color mix node set to value with the Fac set to .5.


All color operations happen before the Shader nodes. After the first shader node only other shader nodes can be used.